1. J OURNAL #3 – A BSOLUTE D ATING 1. Divide the following numbers in half a) 100 b) 50 c) 25 d) 12.5 2. What were four laws or rules for relative dating? 3. How is relative dating different from absolute dating?

2. A BSOLUTE D ATING Objective: Understanding how rocks are given an age based on radioactive elements.

3. A BSOLUTE D ATING Absolute Dating An actual number of years When events occurred and organisms lived Exact age

4. U NSTABLE R ADIOACTIVE D ECAY N UCLEI Radioactive Decay All rocks, artifacts and fossils are made up of elements and isotopes

5. I SOTOPES Isotopes: variation of the same elements with a different number of neutrons

6. H ALF -L IFE Half-Life The time it takes for half of the atoms in an object to decay into another element; Constant and never changes Radioactive nuclei decay at a known rate which is called their half-life

7. H ALF -L IFE Parent Material – radioactive isotope Daughter Product – the result of the radioactive isotope decaying by its half-life

8. H ALF -L IFE Ratio of Daughter Products Used to determine the exact age of rocks, artifacts, and fossils